The field relates generally to monitoring a dynamic system, and more specifically, to methods and systems for using environmentally immune modulation for precise measurement of multiple attributes of a dynamic system.
Resonant sensors, such as gyroscopes, accelerometers, pressure sensors, measure dynamic systems, such as turbines. The dynamic systems include many different attributes. Some of the attributes are system attributes, i.e., attributes that are directly affected by the operation of the dynamic system itself. Other attributes are environmental attributes, i.e., attributes that are affected by the environment of the dynamic system. For example, on a turbine, system attributes may include revolutions per minute (RPM), vibration, and internal temperature. Environmental attributes may include external temperature, humidity, and acceleration in the case of a jet turbine. Other attributes are sensor attributes that affect the operation of the resonant sensor. For example, sensor attributes may include, but are not limited to, temperature-factor, stiffness, gap, resistivity, and resonant frequencies.
When using a sensor to measure a system attribute of a dynamic system, the sensor attributes or the environmental attributes may affect the readings of the measured attribute. For example, when measuring angular rotation, the vibration, the external temperature, and the humidity may affect the reading of the sensor, in addition to the actual angular rotation of the dynamic system. Therefore changes to these non-measured attributes may affect the sensor, thereby affecting the sensor output via the internal sensor attributes or readings of the sensor. For example, a raise in the environmental attribute of temperature may change the reading for the measured attributes of angular rotation, even if the angular rotation of the dynamic system has not changed. Many known measuring systems, with only one sensor, are unable to determine how much a change in the measured attribute or changes in the system or environmental attributes produced the current output reading of the measured attribute. Furthermore, the environment of the sensor may affect the calibration of the sensor, with changes in the environment attributes affecting the accuracy of the output of the sensor.
To counteract this effect, some known systems have used multiple sensors to measure multiple of attributes (both system and environmental) of a dynamic system. Then the readings from the multiple attributes are compared to improve the accuracy of the readings of each sensor, through a calibration process. However, this technique is expensive as it requires multiple sensors to measure multiple attributes (both system and environmental). Furthermore, in some dynamic systems or situations, different system and environmental attributes may affect the measured attribute more than others. One of the other disadvantages of the conventional calibration approach is the time required to properly calibrate the device.